A class of machines exists in the art generally known as “scroll” machines for the displacement of various types of fluids. Such machines may be configured as an expander, a displacement engine, a pump, a compressor, etc., and the features of the present invention are applicable to any one of these machines. For purposes of illustration, however, the disclosed embodiments are in the form of a hermetic refrigerant compressor.
Generally speaking, a scroll machine comprises two spiral scroll wraps of similar configuration, each mounted on a separate end plate to define a scroll member. The two scroll members are interfitted together with one of the scroll wraps being rotationally displaced 180° from the other. The machine operates by orbiting one scroll member (the “orbiting scroll”) with respect to the other scroll member (the “fixed scroll” or “non-orbiting scroll”) to make moving line contacts between the flanks of the respective wraps, defining moving isolated crescent-shaped pockets of fluid. The spirals are commonly formed as involutes of a circle, and ideally there is no relative rotation between the scroll members during operation; i.e., the motion is purely curvilinear translation (i.e., no rotation of any line in the body). The fluid pockets carry the fluid to be handled from a first zone in the scroll machine where a fluid inlet is provided, to a second zone in the machine where a fluid outlet is provided. The volume of a sealed pocket changes as it moves from the first zone to the second zone. At any one instant in time there will be at least one pair of sealed pockets; and where there are several pairs of sealed pockets at one time, each pair will have different volumes. In a compressor, the second zone is at a higher pressure than the first zone and is physically located centrally in the machine, the first zone being located at the outer periphery of the machine.
A compressor may include a shell assembly, a first scroll member located within the shell assembly and including a first end plate and a first spiral wrap extending from the first end plate, and a second scroll member located within the shell assembly, supported for orbital movement relative to the first scroll member and including a second end plate and a second spiral wrap extending from the second end plate and meshingly engaged with the first spiral wrap to form compression pockets. The first scroll member may define a fluid injection port and the second scroll member may define a passage in communication with the fluid injection port and at least one of the compression pockets to provide pressurized vapor from the fluid injection port to the at least one of the compression pockets.
The compressor may additionally include a drive shaft engaged with the second scroll member and the fluid injection port may extend through the first end plate and the passage may extend through the second end plate and may be intermittently in communication with the fluid injection port. Initial communication between the fluid injection port and the passage may occur just after an outermost one of the compression pockets is formed by being sealed off from a suction pressure region of the shell assembly. Communication between the fluid injection port and the passage may be terminated after ninety degrees of rotation of the drive shaft after the initial communication between the fluid injection port and the passage occurs. Communication between the fluid injection port and the passage may be terminated after ninety degrees of rotation of the drive shaft after an outermost one of the compression pockets is formed by being sealed off from a suction pressure region of the shell assembly. The first scroll member may be axially fixed relative to the shell assembly and the second scroll member may be axially displaceable relative to the shell assembly and the first scroll member.
The passage may include a first axial passage extending partially through the second end plate and in communication with the fluid injection port, a radial passage extending from the first axial passage through the second end plate and a second axial passage extending from the radial passage and in communication with the at least one of the compression pockets. The compressor may include a third axial passage extending from the radial passage and in communication with another one of the compression pockets.
The compressor may additionally include a vapor injection system having a pressurized vapor source in communication with the fluid injection port. The shell assembly may include an end cap and the vapor injection system may include a fluid line extending through the end cap and providing the pressurized vapor source to the fluid injection port. The compressor may include a drive shaft engaged with the second scroll member and the fluid injection port may extend through the first end plate and the passage may extend through the second end plate and may be intermittently in communication with the fluid injection port. Initial communication between the fluid injection port and the passage may occur just after an outermost one of the compression pockets is formed by being sealed off from a suction pressure region of the shell assembly. Communication between the fluid injection port and the passage may be terminated after ninety degrees of rotation of the drive shaft after the initial communication between the fluid injection port and the passage occurs. Communication between the fluid injection port and the passage may be terminated after ninety degrees of rotation of the drive shaft after an outermost one of the compression pockets is formed by being sealed off from a suction pressure region of the shell assembly. The first scroll member may be axially fixed relative to the shell assembly and the second scroll member may be axially displaceable relative to the shell assembly and the first scroll member.